Cam tooth generating mechanism



Feb. 27, 1934. F. MARRIOTT r-:r AL 1,949,052

CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1952 3 Sheets-Sheet 1 47TOP/WW Feb. 27, 1934.

F. MARRIOTT ET AL CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1932 3Sheets-Sheet 2 Feb.27, 1934. F, MARRlOTT Er AL 1,949,062

CAM TOOTH GENERATING MECHANISM Filed Sept. 12, 1932 3 Sheets-Sheet 3 7 j17 15 W l 13 J '3 r 3 H1 a *0) y 5 q Z 15 Patented Feb. 27, 1934 PATENTOFFICE CAM TOOTH GENERATING MECHANISM Frank Marriott and ConstantineNeklutin, Ferguson, Mo.

Application September 12, 1932 Serial No. 632,768

Claims.

This invention relates generally to machinetools and has more particularreference to a certain new and useful improvement in cam-toothgenerating mechanism, our invention having for its prime object theprovision of mechanism for generating on suitable stock an exact,accurate, and precise helical or spiral cam-tooth having a varyinghelix-angle, or, conversely, a groove corresponding thereto.

And with the above and other objects in view, our invention resides inthe novel features of form, construction, arrangement, and combinationof parts hereinafter described and pointed out in the claims.

In the accompanying drawings (three sheets) Figure 1 is a sideelevational view of a camtooth-generating mechanism of our invention,shown in connection with fragmental portions of an operatingmachine-tool and the work being shown with its tooth in process offormation;

Figure 2 is an enlarged end view of the mechanism';

5 views illustrating the corresponding positions of the cutter atsimilar successive stages of the formation of the tooth on thework.

Referring now more in detail and by reference characters to thedrawings, which illustrate a preferred embodiment of our invention, Adesignates any conventional machine-tool, preferably of themilling-machine type, which, for our pres ent purpose, may be said toinclude a frame, of which merely fragmentary portions of thespindie-housing a and table-bracket b are shown. From thespindle-housing a, suitably projects a spindle-head l, and projectingfrom the spindlehousing a" over the spindle-head 1, is an overarm 2, onthe outer end of which is mounted a depending so-called arbor-support 3.

Rotarily mounted in the spindle-head l, is a spindle 4, which isprovided with a taper-bore 5 in the usual manner, the arbor-support 3having a hushed aperture 6 in horizontal registration with the spindle 4and its bore 5, as best seen in Figures '2 and 3.

B designates a bevel-drive attachment or head, which at one end isattached to a hub 7 mounted on a suitably projecting portion 8 of "thespindlehead 1 for rotation about the axis of the spindle 4. The hub '7carries a bearing 9, preferably of the ball or roller type, disposedregistration with the spindle-bore 5. Supported in and through thebearing 9, is a shaft 10, which includes a taper-shank 11 having drivingengagement with the taper-bore '5 of the spindle 4.

The shaft 10 projects into the head B and car-- ries a bevel-pinion 12,which meshes with a bevelgear 13 carried by a cutter-shaft 14 supportedat a right-angle to the spindle-axis by suitable upper and lowerbearings 15, 16, respectively, preferably also of the ball or rollertype, the shaft and gear assembly 13- 14 being inserted through the topof the head B and suitably retained therein, as by a closure 17.

At its lower end, the shaft 14 depends below the head B and carries .acutter 18of the sO-called end-mill type having side cutting edges 56 andend cutting edges 57, the cutter 18 including a taper shank 1'9 engaginga corresponding bore provided in and through the lower end of the shaft14, as best seen in Figure 3.

Presented from the head 13 toward, and engaging the hushed aperture 6of, the arbor-support 3, is a shaft 20, which carries a helicalgear 21normally restrained against rotation by means presently appearing, butactuable during the operation of the machine for permitting revolutionof the head B on its horizontal axis. Such movement of the head B iseliected "by a pair of weights 22 suspended from respective flexiblecables, chains, or the like '23 trained over pulleys 24 supported fromthe opposite ends of a beam 25 suitably mounted on, and laterallyextending on each side of, the over-arm 2, the chains 23 being attachedto a sheave-wheel 26 mounted on the hub '7 for normally biasing the"head B for movement in counter-clockwise direction, reference beingmade to Figure 1.

conventionally, the machine-tool A includes a table 27, which, in thepresent instance, is clamped or fixed in position by means not shown,the usual table-feed screw 28, for the purposes of our invention, beingdisconnected from the table 27.

Mounted on the table 2'7, is a fixture C rotarily supporting an arbor 29disposed at a right angle to the axis of the spindle 4 and in thevertical plane of swinging movement of the cutter 18, the

arbor 29 including a shaft 30 extending longitudinally of the table 2'7.The arbor-shaft 30 carries a worm-gear 31 meshing with a worm 32 on across-shaft 33, the latter, in turn, carrying a worm-gear 34 meshingwith a worm 35 on a shaft 36 extending also longitudinally of the table27 to an end thereof, where the shaft 36 carries a spur-gear 3'7,meshing with a suitably adjustable idler-gear 38 driven by a gear 39mounted on the adjacent end of the feed-screw 28, whereby the arbor 29is driven at a suitably reduced speed from and by the feed-screw 28-,the arbor 29 being rotated, in the present instance, in clockwisedirection, reference being made to Figure 2.

A cutter-feed shaft 40 is also mounted in the fixture C parallel withthe arbor 29, the shaft 40 carrying at one end a gear 41 meshing withthe gear 21 on the head B at a one-to-one ratio.

The shaft 40 at its other end carries an index plate or sector 42provided with an arcuate series of indexing apertures 43, 44, 45,respectively, adapted to be slidably engaged by a pin 45 shiftablysupported on a bracket 47 upstanding from the fixture C for retainingthe sector 42 in particular shifted positions, the sector 42 during thetooth-generating operation being moved successively in clockwisedirection, that is, from left to right in Figure 2.

When the aperture 43 is in registration with, and engaged by, the pin46, the head B is retained in rotated position in the axial verticalplane of the arbor 29 for disposing the cutter 18 at an angle of 22 tothe left of the vertical center of the axis of the head B, or at anangle of 67 to the longitudinal axis of the arbor29, as seen in Figures1, 2, and 5.

When the pin 46 engages the aperture 44, the cutter 18 is disposed at anangle of 22 to the right of the vertical center of the head B, as seenin Figure 7, and when the pin 46 engages the aperture 45, the cutter 18is disposed at an angle of 6'7 also to the right of the vertical centerof the head B, as seen in Figure 8.

Axially aligned with the shaft 40, is an oscillatory indexing shaft 48,on one end of which is mounted an indexing arm 49 swingable across theface of the sector 42 and carrying a slidable pin 50 disposed forshiftable movement into and out of the respective apertures 43, 44, 45,in the sector 42, as the case may be. The shaft 48 extends parallel withthe arbor-shaft 30 and at its other end carries a pinion 51 meshing witha rack 52 slidably mounted for transverse movement in the fixture C. Atits inner end, the rack 52 carries a roller 53 for co-operation with acam 54 mounted on the adjacent end of the arbor-shaft 30, as best seenin Figures 1 and 2.

The cam 54 includes a fall or workingportion a, a rise or return portionis. and a dwell'c. The proportions of the cam 54 will vary according tothe work, as presently more particularly appearing; however, in thepresent instance, the working portion a includes an angle ofapproximately 200 of arc and is effective for permitting shifting of therack 52 for rotating the shaft 48 and arm 49 through on angle of 45 inclockwise direction, reference being made to Figure 2. The rack 52 isreturned to initial position by the cam return portion b and is retainedin such position by the dwell portion 0 of the cam 54.

D designates the work, which comprises a cylindrical-body in whichperipherally a helical tooth or thread 55 of irregular or varyinghelixangle is to be formed by our mechanism, the finished tooth 55comprising an end or entering helical portion d merging into an annularor non-helical portion 6 at right angles to the axis of the cam and, inturn, merging into an end helical departure portion f, as best seen inFigures 9 to 13, inclusive.

1n the use and operation of our mechanism, the body D may be cut from abar of solid stock as in the present instance, or the body D may berough cast and the tooth-form cut from the casting. In either case, thetooth-generating operation is performed by milling or cutting one sideface of the tooth 55, then crossing over and cutting the other side faceof the tooth 55, the work revolving approximately two revolutions, moreor less, during the generating operation.

In setting the mechanism for generating a particular cam tooth, thearbor-shaft 30 is rotated until the roller 53 of the rack 52 engages thecam 54 at the beginning of the cam work-portion a, the arm 49 being thendisposed at extreme lefthand position, reference being made to Figure 4.The head B is then manually rotated for swinging the sector 42-at theleft until its aperture 43 is in registration with the shifter-pin 50 ofthe arm 49. The pin 50 is then inserted into the sector-aperture 43 forlocking the head B in such rotated position, the cutter 18 being thendisposed at an angle of 67 to the left of the vertical Zenter of thehead B, as also shown in Fig- A cylindrical body D of suitable length isthen mounted on the arbor 29 with its center in vertical registrationwith the vertical center of the head B.

The machine tool A is then started in operation, which, through thespindle 4 effects rotatory actuation of the cutter 18 and through thefeedscrew 28 effects rotatory actuation of the arborshaft 30 and itscarried work D.

Rotation of the arbor-shaft 30 likewise rotates the cam 54 forpresenting the falling or working cam-portion a to the roller 53, and,since the weights 22 bias the head 13 for rotatory movement tending topress the roller 53 against the cam 54, the rack 52 will shift forpermitting the arm 49 and its pin-connected sector 42 to swing clockwisethrough an angle of 45, as seen in dot-dash lines in Figure 4, for, inturn, allowingthe head B to rotate counterclockwise through an angle of45 against the work, the work D meanwhile also rotating as the cutter 18is brought into engagement therewith for forming one side face of thehelical end-portion cl of thev tooth 55, as seen in Figures 5 and 10.

Meanwhile, the operator grasps the anchor-pin 46 and quickly shifts thesame into the aperture 43 as the latter is broughtinto registrationtherewith. The pin 46, as it enters the aperture 43 looks the sector 42to the'anchor bracket 47 and, at the same time, releases the pin 50therefrom, the head B then being likewise secured against rotatorymovement, with the cutter 18 disposed at an ange of 22 from the verticalcenter of the head B, as seen in Figures 5 and 10. 3

At such time, the return cam-portion b engages the roller 53 and shiftsthe rack 52 for swinging the arm 49 counterclockwise through an angle of45 until the shifter-pin 50 is in registration with the sector-aperture44, as shown by dot-dash lines in Figure 5. The operator then shifts thepin 50 into the aperture 44, thus locking the arm 49 to the sector 42.Meanwhile, the roller 53 engages the dwell cam-portion c for holding thesector 42 against rotation, the operator then withdrawing the anchor-pin46 from the aperture 43, thus releasing the sector 42 from the bracket47 in readiness for the next ensuing cycle of cam-released movement ofthe arm '49.

The head B is in such described manner locked against movement, with thecutter 18, as has been said, disposed at an angle of 22 from thevertical center of the head B, while the cam 54 rotates until thebeginning of the working cam-portion a is again brought opposite theroller 53, the work D being correspondingly rotated and the cutter 18forming one side face of the annular or non-helical portion e of thetooth 55, as seen in Figures 1, 2, 6 and 11. V

The falling or working cam portion a is new again presented to theroller 53, whereby the rack 52 is allowed to shift, responsive to biasof the weights 22, for swinging the arm 49 and sector 42 clockwisethrough an angle of 45 for, in turn, permitting the head B to rotatecounterclockwise again through an angle of 45 against the work, the workD also rotating as the cutter i8 now crosses over to the other side ofthe tooth portion 6, as shown in dot-dash lines in Figures '6 and 11,the cutter 18 on its one side engaging its cutting edges 56 with oneside face of the departure helical end portion 1 of the tooth 55. At thesame time on its other diametrically opposite side the cutter 18 engagesits cutting edges 56 with the other side face of the entering helicalend portion 01 of the tooth 55, as best seen in Figures '7 and 12, thewidth of the channel or groove 9 between the tooth portions 11 and beingthus, as will be seen, equal to the diameter of the cutter 18.

Meanwhile, the operator again grasps the anchor-pin 46 and shifts thesame into the aperture 44 as the latter is brought into registrationtherewith, the shifter-pin 50 being displaced from the sector 42 forreleasing the arm 49, while the pin 46 locks the sector 42 and head Bagainst rotatory movement, the cutter 18 being then disposed at an angleof 22 from the vertical center of the head B, as also seen in Figure 7.

Now the return cam-portion b again engages the roller 53 and shifts therack 52 for swinging the arm 49, as before, through an angle of 45 forbringing the pin 50 into registration with the sector-aperture 45, asshown by dot-dash lines in Figure 7. The operator then shifts the pin 50into the aperture 45, thus once more locking the arm 49 to the sector42. Meanwhile, the roller 53 engages the dwell cam-portion c for holdingthe sector 42 against rotation, the operator withdrawing the pin 46 fromthe aperture 43 for releasing the sector 42 from the bracket 47 inreadiness for the next ensuing movement of the arm 49.

The head B is thus again locked against movement with the cutter 18 inits described position at an angle of 22 from the vertical center of thehead B, while the cam 54 rotates until the beginning of the cam-portiona is brought into registration with the roller 53, the work D beinglikewise rotated while the cutter 18 generates or forms the other sideface of the annular portion e of the tooth 55, as will be understoodfrom Figures 8 and 13.

The falling or working cam-portion a is now for a third time presentedto the roller 53, the rack 52 then shifting, as before, for swinging thearm 49 and sector 42 clockwise through an angle of 45, the head Brotating counterclockwise through an angle also of 4. and, the work Dcontinuing its revolution, the cutter 18 cuts and generates the otherface of the departure helical end-portion f of the tooth 55, the cutterfinally being disposed wholly away from the work D at an angle of 67 /2from the vertical center of the head B, as also seen in Figures 8 and13.

The machine is then stopped and the finished work D' is removed from thearbor 29. The arbor-shaft 30 is then allowed to rotate for engaging thereturn cam-pcrtion b with the roller 53 for shifting the arm 49counterclockwise through an angle of 45, while the operator withdrawsthe pin 50 from the aperture 45 and manually rotates the head B untilthe sector-aperture 43 is in registration with the pin 50, the latterthen being inserted into the aperture 43 as the beginning of thecam-portion a comes into registration with the roller 53, the severalparts being then restored to respective initial positions for repetitionof the tooth-generating cycle as described.

While the side-cutting edges 56 of the cutter 18 are generating thetooth 55, the end cutting edges 57 of the cutter 18 are cutting thebarrelportions h of the work D. It will be seen that, by varying theprojection of the cutter 18 from the horizontal axis of the head 13, thearcuate contour of the barrel-portions it may be varied suitably to theradius of movement of a lever, gear, or other like element to beactuated by the finished worm-cam D. Furthermore, by suitably varyingthe conformation of the cam 54, and by varying the spacing and number ofapertures in the sector 42, correspondingly varying shapes of teeth maybe generated on the work D, as may best serve the intended purpose.

It will be understood that other changes and modifications in the form,construction, arrangement, and combination of the several parts of theapparatus may be made and substituted for those herein shown anddescribed without departing from the nature and principles of ourinvention.

Having thus described our invention, what we claim and desire to secureby Letters Patent is,-

1. Mechanism for generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mountedfor rotatory movement about the axis of the spindle, a cutter carried bythe head for rotation by the spindle, an arbor for rotarily supportingthe work in co-operation with the cutter, and means having operableassociation with the head and arbor for intermittently rotarilyactuating the head for varying the angular-engaging relation of therotating cutter with the rotating work.

2. Mechanism for generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mountedfor swingable movement about the axis of the spindle, a cutter swingablewith the head and supported by the head for rotation by the spindle, anarbor for rotarily supporting the work in co-operation with the cutter,and means having operable association with the head and includingindexing mechanism associated with the arbor for swingably at intervalsduring the rotation of the arbor and its supported work actuating thehead for varying the angular-engaging relation of the rotating cutterwith the rotating work.

3. Mechanism for generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mountedfor swingable movement about the axis of the spindle, a cutter swingablewith the head and angularly supported by the head for rotation by thespindle, an arbor for supporting the work in co-operation with thecutter, means for rotarily actuating the arbor, and means includingindexing mechanism associated with and responsive to actuation of thearbor and having operable connection with the head for rotarily atintervals during the rotation of the arbor swingably actuating the headand its carried cutter for varying the angular-engaging relation of therotating cutter with the rotating work.

4. Mechanism for generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mounted for swingable movement about the axis of the spindle, a cutterswingable with the head and angularly disposed on the head for rotationby the spindle, an arbor for supporting the Work in co-operation withthe cutter, means for normally biasing the head for feeding the rotatingcutter longitudinally on the work, means for rotarily actuating thearbor, a rotary cam actuable in synchronism with the arbor, and meansoperable responsively to actuation of the cam for controlling the biasedfeeding movement of the cutter.

5. Mechanismfor generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mountedfor swingable movement about the axis of the spindle, a cutter swingablewith the head and carried by the head for rotation by the spindle, arotary arbor for supporting the work in cooperation with the cutter,means normally biasing the head for feeding the rotating cutterlongitudinally on to the work, means for rotarily actuating the arbor, arotary cam actuable in synchronism with the arbor, and mechanism forcontrolling the biased feeding movement of the cutter, said mechanismincluding an indexing plate having rotative operative connection withthe head and a series of indexing apertures, and an oscillatory memberactuable responsively to said cam and engageable with successiveapertures.

6. Mechanism for generating a helical camtooth having a varyinghelix-angle comprising, in combination, a rotary spindle, a head mcuntedfor swingable movement about the axis of the spindle, a cutter swingablewith the head and carried by the head for rotation by the spindle, arotary arbor for supporting the work in cooperation with the cutter,means normally biasing the head for feeding the rotating cutterlongitudinally on the work, means for rotarily actuating the arbor, arotary cam actuable in syn chronism with the arbor, and mechanism forcontrolling the biased feeding movement of the cutter, said mechanismincluding an indexing plate having rotative operative connection withthe head and a series of indexing apertures, a

rack reciprocatorily actuable by the cam, and an oscillatory armactuable by the rack and engageable with successive apertures.

'7. In an apparatus for generating a helical tooth of varyinghelix-angle, the combination with a rotary spindle, of a head forswingable movement about the axis of the spindle, mechanism supported bythe head for rotatory actuation by and with the spindle, a rotary shaftdisposed angularly with respect to the spindle and actuable by and withsaid mechanism, a cutter mounted on said shaft, means for rotarilysupporting the Work, and mechanism co-operable with said means foreifecting swingable actuation of the head about the spindle for feedingthe rotating cutter longitudinally on the work.

8. In an apparatus for generating a helical tooth of varyinghelix-angle, the combination with a rotary spindle, of a head forswingable movement about the axis of the spindle, mechanism supported bythe head for rotatory actuation by and with the spindle, a rotary shaftdisposed angularly with respect to the spindle and actuable by and withsaid mechanism, a cutter mounted on the shaft, means for rotarilysupporting the work, and mechanism co-operable with said means foreffecting swingable actuation of the head about the spindle for feedingthe cutter longitudinally on the work, said last mechanism including agear on the head, a feed-shaft, a gear on the feed-shaft forco-operation with the first gear, an indexing plate on the feedshafthaving a series of indexing apertures, and a member for engagingsuccessive indexing apertures.

9. In an apparatus for generating a helical tooth of varyinghelix-angle, the combination with a rotary spindle, of a head forswingable movement about the axis of the spindle, mechanism supported bythe head for rotatory actuation by and with the spindle, acutter-supporting shaft disposed angularly with respect to the spindleand actuabie by and with said mechanism, a cutter mounted on said shaft,means for rotarily supporting the work, mechanism co-operable with saidmeans for controlling swingable actuation of the head about the spindlefor feeding the cutter longitudinally on the work, and means for biasingthe head for actuation thereof responsively to actuation of saidcontrolling mechanism.

ii). In an apparatus for generating a helical tooth of varyinghelix-angle, the combination with a spindle, of a head forswingablemovement about the axis of the spindle, mechanism supported bythe head for rotatory actuation by and with the spindle, a shaftdisposed angularly with respect to the spindle and actuable by and withsaid mechanism, a cutter mounted on the shaft, a gear on the head, anarbor for rotarily supporting the work, a feed-shaft, a gear on thefeedshaft for co-operation with the head-gear, an indexing plate on thefeed-shaft having a series of indexing apertures, a member for engagingsuccessive indexing apertures for locking the head in selectively swungpositions relatively to the spindle, a cam actuable by and withthearbor, an oscillatory indexing shaft for actuation responsively tooperation of the cam, and a second member carried by said latter shaftfor engaging successive indexing apertures for swinging the head betweensaid selectively locked positions on release of said first member fromsaid indexing plate for feeding the cutter longitudinally on the work.

11. Helical-cam-tooth generating mechanism comprising, in combination,means for rotarily supporting the work, an end-milling cutter, means forrotating the cutter, means for normally biasing the cutter foroscillatory movement, and means for interrupting oscillatory movement ofthe cutter at predetermined intervals during rotation of the work forvarying the helix angle of the tooth being formed upon the work.

12. Helical cam-tooth generating mechanism comprising, in combination,means for rotarily supporting the work, an end-milling cutter, means forrotating the cutter, means for supporting the cutter for swingablemovement longit'udinally of the rotating work, means for normallyswingably biasing the cutter supporting means, and means forinterrupting swingable movement of the cutter at predetermined intervalsduring rotation of the work for varying the angular relation of thecutter with the work for forming upon the Work a tooth comprisingentering and departing helical sections and a central non-helicalsection.

13. Cam-tooth generating mechanism comprising, in combination, a headdisposed for swingable movement, a rotary arbor for supporting the workin registration with the center of the head, a rotary cutter supportedfor engagement with the work by, and swingable relatively to the workwith, the head, means for rotating the cutter, means for normallyswingably actuating the head for shifting the cutter for varying theangular-engaging relation of the rotating cutter with the rotating work,and mechanism actuable responsive to and during rotation of the arborfor interrupting swingable movement of the head and cutter at intervalsin the rotation of the work for successively cutting upon the work theopposite side faces of the desired tooth.

14. Cam-tooth generating mechanism comprising, in combination, a headdisposed for swingable movement, a rotary arbor for supporting the workin registration with the center of the head, a rotary cutter supportedfor engagement with the work by, and swingable relatively to the workwith, the head, means for rotating the cutter, means for normallyswingably actuating the head for varying the angular-engaging relationof the rotating cutter with the'rotating work, and means includingindexing mechanism actuable responsive to and during rotation of thearbor for interrupting swingable movement of the head at intervals inthe rotation of the work for successively cutting upon the work theopposite side faces of the tooth.

15. Cam-tooth generating mechanism comprising, in combination, a rotarycutter, a rotary arbor for supporting the work for engagement by thecutter, an oscillatory head for supporting the cutter for swingablemovement in the plane of the longitudinal axis of the work, means forrotating the cutter, means for normally swingably actuating the head forvarying the angular-engaging relation of the rotating cutter with therotating work, and mechanism actuable during and responsive to rotationof the arbor for effecting interrupting at intervals swingable movementof the head and its supported cutter relatively to the work.

16. Cam-tooth generating mechanism comprising, in combination, aswingable head, a rotary arbor for supporting the work in registrationwith the center of the head, a rotary cutter supported for engagementwith the work by, and swingable relatively to the work with, the head,means for rotating the cutter, means for swingably actuating the headfor angularly shifting the cutter relatively to the rotating work, andmeans actuable responsive to and during Irrotation of the arbor forinterrupting swingable movement of the head at intervals in the rotationof the work.

17. Cam-tooth generating mechanism comprising, in combination, aswingable head, a rotary arbor for supporting the work in registrationwith the center of the head, a rotary cutter supported for engagementwith the work by, and swingable relatively to the work with, the head,means for rotating the cutter, means for swingably actuating the headfor angularly shifting the cutter relatively to the rotating work, andindexing mechanism actuable responsive to and during rotation of thearbor for interrupting swingable movement of the head at intervals inthe rotation of the work.

18. Cam-tooth generating mechanism comprising, in combination, aswingable head, a rotary arbor for supporting the work in registrationwith the center of the head, a rotary cutter supported for engagementwith the work by, and swingable relatively to the work with, the head,means for rotating the cutter, means for swingably actuating the headfor angularly shifting the cutter relatively to the rotating work, andindexing mechanism including a cam actuable by and during rotation ofthe arbor for interrupting swingable movement of the head at intervalsin the rotation of the work.

19. In an apparatus for generating a helical tooth of varying helixangle, a housing, a spindle having a bearing in the housing forrotation, a head having a hub mounted on the housing for rotation aboutthe axis of the spindle, a cutter-supporting shaft angularly supportedby the head with respect to the spindle, meshing gears on the spindleand shaft, and means including opposed weighted flexible members havinoperable connection with the hub for rotarily actuating the head.

20. Helical-cam-tooth-generating mechanism comprising, in combination,means for rotarily supporting the work, a rotary cutter, means includinga rotarily actuable cutter-supporting head for arcwise shifting thecutter in the plane of the longitudinal axis of the work for varying theangular-engaging relation of the rotating cutter with the rotating work,and means oper- ,:able for restraining rotary actuation of the head atsuccessive intervals in the rotation of the work for temporarily holdingthe cutter in selected angular positions with respect to the work.

FRANK MARRIOTT. CONSTANTINE NEKLUTIN.

